This proposal is to continue our studies on the measurement of bone-ligament-bone junction strength and on the strength of isolated ligaments. In addition, selected biochemical (hydroxyproline), anatomical (weight, length, weight/length), rheological (elastic stiffness, failure energy), and histological (light and EM) measurements are obtained from animals assigned to aging, trained, immobilized, centrifuged, BAPN injected, an surgically repaired groups. Most of these measurements are obtained from rats but dogs are also studied and plans are underway to use primates in the immobilization and training studies.